Featuring a lightweight contest between Jorge Gurgel and Joe Duarte, Strikeforce Challengers 18 takes place Aug. 12 at The Pearl at the Palms Casino Resort in Las Vegas.

It's not clear if Green vs. Vieira will be part of the Showtime-televised main card.

Green, a three-and-a-half-year pro, has spent much of his career with KOTC, though he's also made appearances with Affliction and Tachi Palace Fights. The 24-year-old, who trains with Pinnacle Jiu jitsu and MMA in California, owns seven knockouts and six submissions in 15 career victories.

Vieira joins the organization with four victories in his past five fights and six wins in his past eight bouts. The Brazilian jiu-jitsu black belt (under Murilo Bustamente), who's put on many entertaining bouts in his native Brazil, has earned submissions in eight of his 12 career victories.

Strikeforce Challengers 18 marks the promotion's second event in Las Vegas. Beginning with July's Strikeforce Challengers 17 card, the prospects-based Challengers Series events now take place at The Pearl at the Palms Casino Resort in Las Vegas.

LAS VEGAS – Big-fight veteran Jorge Gurgel promised he was finally going to use his vaunted jiu-jitsu. Joe Duarte had other plans.

The Guam native showed excellent takedown defense and competent counterstriking on the feet as he earned a unanimous-decision win over Gurgel.

The bout served as the featured contest of Saturday's Strikeforce Challengers 18 event, which took place at The Pearl at The Palms Casino Resort in Las Vegas.

The evening's main card aired on Showtime.

Gurgel opened the fight more patient than in previous appearances, looking to feel out Duarte and pick his shots. He did find himself in a few early firefights, but he reset and landed the first significant blow of the night with a stinging low kick. The action stayed tight through the round, as Duarte answered in spots, and a late takedown gave him a reason to boast a win, though Gurgel did seem the busier fighter.

In the second, Gurgel again opened moved forward with strikes. However, Duarte appeared to find his range with a bit more frequency. Gurgel looked to force the action to the floor, but Duarte shucked off his attempt with relative ease. The two continued to trade on the feet, but it was Duarte who did the damage with more precise blows.

In the third, Gurgel continued to dive forward with takedown attempts, but Duarte again showed excellent defense and reversed the attempt as he fell to mount. Gurgel did scramble quickly to guard, but he found little opportunity for offense once there. With a little more than a minute remaining, Duarte moved to his feet and allowed his opponent to follow. Gurgel pressed forward once again, but Duarte landed another late takedown, which looked to have sealed the result. The judges agreed, giving Duarte the unanimous-decision win despite Gurgel's aggressive striking in the final round.

"Jorge, I was a fan of his," Duarte said after the victory. "I knew training for this fight was going to be hard. … I knew it wasn't going to be an easy fight."

With the biggest win of his career, Duarte (10-2 MMA, 2-0 SF) now carries a five-fight win streak. Gurgel (14-8 MMA, 1-2 SF) found himself on the short end of a yet another entertaining matchup.

James claims victory in late rally

In the night's middleweight co-feature, Nate James and Danillo Villefort engaged in a back-and-forth affair, but the surging James used a late swing in momentum to claim victory.

The opening round saw Villefort looking sharp, earning a crisp toss takedown and nearly securing a rear-naked choke before the end of the round.

In the second, Villefort again came out as the aggressor, controlling, the action, but he appeared to fade in the closing minutes. It would prove a pivotal moment in the bout.

In the third, Villefort again looked to push, but James found his rhythm on the feet. Villefort decided to take the action to the floor, but he twice wound up in bottom position, allowing James to take the frame. It would also earn him the fight via unanimous decision.

"I felt in control the whole fight," James said after the win. "Even when he had my back, I didn't feel threatened.

"I'd just like to thank my entire team. They prepared me well for this fight, and I can't wait to get back out there."

In lightweight action, a scrappy Eric Wisely gave opponent Pat Healy a few moments of concern with earnest submission attempts, but it was "Bam Bam" who continually worked to top position and earned a hard-fought decision win.

Wisley has his best moments early in the fight, making a real claim for the opening round and keeping the second tight with work from his back. But with the result uncertain late in the contest, Healy's size advantage seemed to wear on his foe as he continued to grind away on the floor. In the end, the fight was close, but Healy did enough to earn the decision result and was ultimately awarded the fight.

"It wasn't my best performance," Healy said. "I've been on ice for a year-and-a-half. I got through this one healthy, so I'm eager to take more fights and continue toward the title."

The veteran Healy (25-16 MMA, 3-1 SF) is now 5-1 in his past six fights. Wisley (18-6 MMA, 0-1 SF) earned respect in the loss of a four-fight win streak but appears best suited for a lighter weightclass.

Rousey continues impressive run in controversial fashion

Top female prospect Ronda Rousey continued her quick ascension up the 145-pound ranks with yet another rapid first-round armbar, though the stoppage came in somewhat suspicious fashion over Sarah D'Alelio.

After working the fight quickly to the ground from the clinch, Rousey locked in her trademark maneuver. While the angle looked awkward, there was a brief verbal reaction from D'Alelio. Rousey briefly released the hold, the re-cranked it as referee Steve Mazzagatti reached in to halt the fight.

The decision was met with boos, but Mazzagatti stood behind the decision, and Rousey was granted the submission win in just 25 seconds.

"I'm happy with the win, but I wish it would have ended less controversially," Rousey said after the win. "I had the armbar in tight. I thought that I heard her say, 'Tap,' so I looked toward the referee, and he stepped in and stopped the fight."

Rousey (3-0 MMA, 1-0 SF), a former Olympic judoka, has yet to fight more than 49 seconds in any of her professional MMA bouts. D'Alelio (4-2 MMA, 0-1 SF) has now dropped two-straight fights.

Bloody "Caveman" earns hard-fought decision

In the night's first Showtime-televised contest, light heavyweight Derrick Mehman survived a second-round gash near his eye to earn a hard-fought decision win over Roy Jones.

It was Jones who looked the aggressor in the opening round, and the second-round wound seemed destined to halt the contest. But Nevada State Athletic Commission doctors allowed the fight to continue, and Mehman seized the opportunity.

Working to top position in the second round and again in the third, Mehman grinded away, even as the blood continued to soak both he and his opponent. Jones appeared to tire in the closing minutes, and the gushing Mehman earned a hard-fought decision win.

"I'm very happy to be fighting for Strikeforce," Mehman said after the win. "The eye didn't really bother me until the end of the second. I'm eager to heal up, get back in the gym and fight again as soon as possible."

Mehman (12-3 MMA, 1-0 SF) is now 4-1 in his past five outings. Jones (6-2 MMA, 0-1 SF) falls to just 1-2 in his past three fights.

In the evening's final un-aired preliminary bout, light heavyweight Gian Villante cruised to a unanimous-decision win over Keith Berry.

Much of the action took place inside of Berry's guard, and Villante tried to score from top position. Still, the action remained relatively stagnant in a bout that left the crowd displeased for much of the 15-minute contest. Still, Villante's time in a controlling position left the winner clear, and he was awarded a clear-cut unanimous decision win.

While he gained few fans, Villante (8-3 MMA, 1-2 SF) earned a much-needed win and snapped a two-fight losing streak. Berry (10-8 MMA, 0-2 SF) has now dropped three-straight fights and will likely return to the regional circuit.

Welterweight Nah-Shon Burrell improved to 2-0 under the Strikeforce banner with a second-round TKO over Wolfslair product Lukasz Les.

Les looked sharp early with crisp striking and an early takedown. But as the round wore on, Burrell regained his positioning and floored his opponent with a huge right hand.

In the second, Les had no success with his takedown attempts, and Burrell continued to land successful strikes. A stinging low kick wobbled Les, and Burrell pounced with blows from top position. While the damage didn't appear too significant, the bout was waved off at the 2:09 mark.

In early welterweight action, Mike Bronzoulis outstruck and outgrappled Chad Leonhardt for two full rounds before ultimately earning a stoppage in the final frame.

Leonhardt showed moments of strength, especially with a few stinging knee strikes and effective takedown defense. But the moderately paced fight was controlled mostly by his opponent. In the final round, Leonhardt staggered his opponent with an early strike, but Bronzoulis buckled his foe with a low kick and then swarmed with punches. Leonhardt couldn't halt the attack, and referee Herb Dean called the fight 90 seconds into the final round.

In the evening's first contest, lightweight submission ace Milton Vieira made his promotional debut in impressive fashion.

The Brazilian briefly traded shots on the feet with opponent Sterling Ford before dragging the action to the floor with an unsuccessful guillotine choke. Vieira switched to a brabo choke, wrenching and adjusting until the hold was secure. With Ford trapped, he chose to sleep rather than tap, and Vieira was pulled off with 11 seconds left in the opening round.

Top female prospect Ronda Rousey continued her quick ascension up the 145-pound ranks with yet another rapid first-round armbar, though the stoppage came in somewhat suspicious fashion over Sarah D'Alelio.

After working the fight quickly to the ground from the clinch, Rousey locked in her trademark maneuver. While the angle looked awkward, there was a brief verbal reaction from D'Alelio. Rousey briefly released the hold, the re-cranked it as referee Steve Mazzagatti reached in to halt the fight.

The decision was met with boos, but Mazzagatti stood behind the decision, and Rousey was granted the submission win in just 25 seconds.

"I'm happy with the win, but I wish it would have ended less controversially," Rousey said after the win. "I had the armbar in tight. I thought that I heard her say, 'Tap,' so I looked toward the referee, and he stepped in and stopped the fight."

Rousey (3-0 MMA, 1-0 SF), a former Olympic judoka, has yet to fight more than 49 seconds in any of her professional MMA bouts. D'Alelio (4-2 MMA, 0-1 SF) has now dropped two-straight fights.

Steve should be forced to pay the loser the Win bonus because he just stole money out of her pocket because he can be mind ****ed by fighters saying "I won and she lost, Call it, cant you see she is knocked out" and they havent even touched gloves yet.

Im obviously joking BUT still. If she didnt tap then you shouldn't stop the fight. Just because the other opponent said she did doesn't actually mean she did. We have Refs for a reason. Do your job Steve or get fired. In any other job when you **** up this badly you obviously run the risk of getting fired or being warned at least. If i screwed a customer of however much money she would have gotten if she got the win then you bet your ass id be back on the street looking for a new job.